Add min_version tests.
These tests use both APIs. This also modifies the inline version negotiation's
error codes (currently only used for DTLS) to align with SSLv23's error codes.
Note: the peer should send a protocol_version alert which is currently untested
because it's broken.
Upstream would send such an alert if TLS 1.0 was supported but not otherwise,
which is somewhat bizarre. We've actually regressed and never send the alert in
SSLv23. When version negotiation is unified, we'll get the alerts back.
Change-Id: I4c77bcef3a3cd54a039a642f189785cd34387410
Reviewed-on: https://boringssl-review.googlesource.com/2584
Reviewed-by: Adam Langley <agl@google.com>